Wordpress.com Terms Of Service clarification?

I'm starting to use Wordpress to make a blog and was sort of confused on something in the terms of use policy. It says that you can be reported for copyright infringement. Is plagiarism the type of copyright information they're talking about because on almost all wordpress blogs I see people using photos of celebrities and other things that they obviously do not own and they don't get reported and kicked off the site. So when wordpress is talking about copyright are they talking about plagiarism in text, images or both